A phosphate buffer is prepared with KH2PO4 at 0.02 M and K2HPO4 at 0.03 M. What is the concentration of phosphate buffer

Answer:

0.171 M

Explanation:

Step 1: Given data

Step 2: Calculate the moles of solute

The molar mass of H₃PO₄ is 97.99 g/mol.

3.35 g × 1 mol/97.99 g = 0.0342 mol

Step 3: Convert "V" to liters

We will use the conversion factor 1 L = 1000 mL.

200 mL × 1 L/1000 mL = 0.200 L

Step 4: Calculate the molarity of the solution

We will use the definition of molarity.

M = moles of solute / liters of solution

M = 0.0342 mol/0.200 L = 0.171 M

Answer:

M =  0.125 M

Explanation:

Given data:

Molarity = ?

Volume of solution = 2 L

Mass of K₂SO₄ = 43.55 g

Solution;

Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.

Formula:

Molarity = number of moles of solute / L of solution

Number of moles of solute:

Number of moles = mass/molar mass

Number of moles = 43.55 g / 174.26 g/mol

Number of moles = 0.25 mol

Molarity:

M =  0.25 mol / 2 L

M =  0.125 M

Answer:

B. The same exact

Explanation:

I think B because in order to be a clone of your parent you have to have the exact same DNA and chromosomes.

Hope this helps :D

A clone has the same exact chromosomes as its parent.

CLONING:

Learn more at: https://brainly.com/question/12483409?referrer=searchResults

Answer:

1.2×10² mmole of Na₂S₂O₃

Explanation:

From the question given above, the following data were obtained:

Volume = 0.6 L

Molarity = 0.2 mol/L

Mole of Na₂S₂O₃ =?

Molarity is simply defined as the mole of solute per unit litre of water. Mathematically, it is expressed as:

Molarity = mole /Volume

With the above formula, we can obtain the number of mole of Na₂S₂O₃ in the solution as illustrated below:

Volume = 0.6 L

Molarity = 0.2 mol/L

Mole of Na₂S₂O₃ =?

Molarity = mole /Volume

0.2 = Mole of Na₂S₂O₃ / 0.6

Cross multiply

Mole of Na₂S₂O₃ = 0.2 × 0.6

Mole of Na₂S₂O₃ = 0.12 mole

Finally, we shall convert 0.12 mole to millimole (mmol). This can be obtained as follow:

1 mole = 1000 mmol

Therefore,

0.12 mole = 0.12 mole × 1000 mmol / 1 mole

0.12 mole = 120 = 1.2×10² mmole

Thus, the chemist added 1.2×10² mmole of Na₂S₂O₃

Explanation:

Valence electrons is the number of electrons in the outermost shell of an atom. For the main group elements, the group number represents the number of valence electrons.

Beryllium

This belongs to the group 2 hence, it has valency of 2.

Nitrogen

This belongs to group 5, hence it has valency of 5.

Oxygen

This belongs to group 6, hence it has valency  of 6.

Fluorine

This belongs to group 7, hence it has valency of 7.

Magnesium

This belongs to group 2, hence it has valency of 2.

Phosphorus

This belongs to group 5, hence it has valency of 5

Sulphur

This belongs to group 6, it has valency of 6

Chlorine

This belongs to group 7, it has valency of 7

Answer:

Beryllium: 2 valence electrons.

Nitrogen: 5 valence electrons.

Oxygen: 6 valence electrons.

Fluorine : 7 valence electrons.

Magnesium : 2 valence electrons.

Phosphorus : 5 valence electrons.

Sulphur : 6 valence electrons.

Chlorine : 7 valence electrons.

Answer:

1000 kJ.mmole / 1000 J.mole

Explanation:

To solve this, we need to analyze the given data.

We have a number which is 87.1 J/mmole.C (I'm assuming it has the J at the beggining because if not, then you are missing some data) and the final result is kJ/mol.C

The only unit that has not changed in the process was the °C, while the mole and J change respectively. In this case, we need to know the conversion factor of mmole to mole and J to kJ.

In the case of a mole:

1 mole --------> 1000 mmole

In the case of Joule:

1 kJ ----------> 1000 J

So the first thing we will do is to change from J to kJ:

87.1 J * 1 kJ / 1000 J = 0.0871 kJ

Now let's convert mmol to mole:

0.0871 kJ/mmole.C * 1000 mmole / 1 mole = 87.1 kJ/mole.C

As you can see, there's is practicly no change at all with the units, so putting all together it would be:

Hope this helps

Answer:

Explanation:

The missing incomplete resonance structure is attached in the image below. From there, we can see the addition of the nonbonding electrons and its' formal charge which makes the resonance structure a complete resonance structure. The others two resonance structure that can be derived from the complete structure is also shown in the image. Out of these three structures, the structure that contributes most to the hybrid is the structure with the negative charge on the oxygen.

Answer:

Explanation:

To find the concentration; let's first compute the average density and the average atomic weight.

For the average density [tex]\rho_{avg}[/tex]; we have:

[tex]\rho_{avg} = \dfrac{100}{ \dfrac{C_{Fe} }{\rho_{Fe}} + \dfrac{C_v}{\rho_v} }[/tex]

The average atomic weight is:

[tex]A_{avg} = \dfrac{100}{ \dfrac{C_{Fe} }{A_{Fe}} + \dfrac{C_v}{A_v} }[/tex]

So; in terms of vanadium, the Concentration of iron is:

[tex]C_{Fe} = 100 - C_v[/tex]

From a unit cell volume [tex]V_c[/tex]

[tex]V_c = \dfrac{n A_{avc}}{\rho_{avc} N_A}[/tex]

where;

[tex]N_A[/tex] = number of Avogadro constant.

SO; replacing [tex]V_c[/tex] with [tex]a^3[/tex] ; [tex]\rho_{avg}[/tex] with [tex]\dfrac{100}{ \dfrac{C_{Fe} }{\rho_{Fe}} + \dfrac{C_v}{\rho_v} }[/tex] ; [tex]A_{avg}[/tex] with [tex]\dfrac{100}{ \dfrac{C_{Fe} }{A_{Fe}} + \dfrac{C_v}{A_v} }[/tex] and

[tex]C_{Fe}[/tex] with [tex]100-C_v[/tex]

Then:

[tex]a^3 = \dfrac { n \Big (\dfrac{100}{[(100-C_v)/A_{Fe} ] + [C_v/A_v]} \Big) } {N_A\Big (\dfrac{100}{[(100-C_v)/\rho_{Fe} ] + [C_v/\rho_v]} \Big) }[/tex]

[tex]a^3 = \dfrac { n \Big (\dfrac{100 \times A_{Fe} \times A_v}{[(100-C_v)A_{v} ] + [C_v/A_Fe]} \Big) } {N_A \Big (\dfrac{100 \times \rho_{Fe} \times \rho_v }{[(100-C_v)/\rho_{v} ] + [C_v \rho_{Fe}]} \Big) }[/tex]

[tex]a^3 = \dfrac { n \Big (\dfrac{100 \times A_{Fe} \times A_v}{[(100A_{v}-C_vA_{v}) ] + [C_vA_Fe]} \Big) } {N_A \Big (\dfrac{100 \times \rho_{Fe} \times \rho_v }{[(100\rho_{v} - C_v \rho_{v}) ] + [C_v \rho_{Fe}]} \Big) }[/tex]

Replacing the values; we have:

[tex](0.289 \times 10^{-7} \ cm)^3 = \dfrac{2 \ atoms/unit \ cell}{6.023 \times 10^{23}} \dfrac{ \dfrac{100 (50.94 \g/mol) (55.84(g/mol)} { 100(50.94 \ g/mol) - C_v(50.94 \ g/mol) + C_v (55.84 \ g/mol) } }{ \dfrac{100 (7.84 \ g/cm^3) (6.0 \ g/cm^3 } { 100(6.0 \ g/cm^3) - C_v(6.0 \ g/cm^3) + C_v (7.84 \ g/cm^3) } }[/tex]

[tex]2.41 \times 10^{-23} = \dfrac{2}{6.023 \times 10^{23} } \dfrac{ \dfrac{100 *50*55.84}{100*50.94 -50.94 C_v +55.84 C_v} }{\dfrac{100 * 7.84 *6}{600-6C_v +7.84 C_v} }[/tex]

[tex]2.41 \times 10^{-23} (\dfrac{4704}{600+1.84 C_v})=3.2 \times 10^{-24} ( \dfrac{284448.96}{5094 +4.9 C_v})[/tex]

[tex]\mathbf{C_v = 9.1 \ wt\%}[/tex]

Answer:

An Alkane

Explanation:

Formula of ethane is CH3-CH3

Answer:

Ethane is the second member of

An alkane

Answer:

6.9428 kg of CO2

Explanation:

1) Use Avogadro's number that states 1 mole = 6.022 x 10^23 particles. Convert 9.5 x 10^25 molecules into moles.

9.5 x 10^25 CO2 molecules[tex]x\frac{1 mole CO2}{6.022 x 10^23}[/tex] = 157.75 moles CO2

2) Convert 157.75 moles of CO2 into grams. CO2's molar mass is 44.01g.

[tex]157.75moles CO2[/tex] [tex]x \frac{44.01g/mol}{1 mole CO2}[/tex] = 6942.79g

3) Convert 6942.79 grams into kilograms (divide by 1000):

6.9428 kg

Answer: Sol:-

Data provided in the question is :-

Atomic mass of isotope -1 = 64 amu

Atomic mass of isotope -2 = 66 amu

Atomic mass of isotope -3 = 67 amu

Atomic mass of isotope -4 = 68 amu

Atomic mass of isotope - 5 = 70 amu

Percentage abundace of isotope - 1 = 48.89 %

Percentage abundance of isotope -2 = 27.81 %

Percentage abundance of isotope - 3 = 4.11%

Percentage abundance of isotope-4 = 18.57%

Percentage abundance of isotope - 5 = 0.62 %

Formula used :-

Average atomic mass of an element =[ {(atomic mass of isotope-1 * percentage abundance of isotope-1) + ( atomic mass of isotope-2 * percentage abundance of isotope -2) + ( atomic mass of isotope -3 * percantege abundance of isotope-3 ) + ( atomic mass of isotope-4 * percentage abundance of isotope-4) + (atomic mass of isotope-5 * percentage abundance of isotope-5)} / 100]

Calculation :-

Put all the value in the formula :-

Average atomic mass of an element = [{(64 * 48.89) + (66 * 27.81) + (67 * 4.11) + (68 * 18.57) + (70 * 0.62)} / 100] amu

= [{(3128.96) + (1835.46) +(257.37) + (1262.76) + (43.4)} / 100] amu

= {(6528.04) / 100} amu

= 65.2804 amu

Average atomic mass of an element is = 65.2804 amu

Then this mass is approximatly equal to atomic mass of zinc so this element would be zinc

atomic mass of zinc = 65.38 \approx 65.2804 amu

Answer:

0.41 atm

Explanation:

A reaction between liquid reactants takes place at 10.0 °C in a sealed, evacuated vessel with a measured volume of 5.0 L. Measurements show that the reaction produced 13. g of sulfur hexafluoride gas. Calculate the pressure of sulfur hexafluoride gas in the reaction vessel after the reaction. You may ignore the volume of the liquid reactants. Round your answer to 2 significant digits.

Step 1: Given data

Step 2: Convert "T" to Kelvin

We will use the following expression.

K = °C + 273.15

K = 10.0 °C + 273.15 = 283.2 K

Step 3: Calculate the moles (n) of SF₆

The molar mass of SF₆ is 146.06 g/mol.

13. g × 1 mol/146.06 g = 0.089 mol

Step 4: Calculate the pressure (P) of SF₆

We will use the ideal gas equation.

P × V = n × R × T

P = n × R × T/V

P = 0.089 mol × (0.0821 atm.L/mol.K) × 283.2 K/5.0 L = 0.41 atm

Answer:

2Al+ 6HNO3 ---- 3H2 + 2Al(NO3)3​

Explanation:

Put coefficient a,b,c, and d for calculation:

a Al + b HNO3 = c H2 + d Al(NO3)3

for Al: a = d

for H: b = 2c

for N: b = 3d

for O: 3b = 9d

Suppose a=1, then d=1, b=3, c=3/2

multiply 2 to make all natural number, a=2, then b=6, c=3, d=2

its true

Potential energy is the stored or latent energy in an object at rest. It’s fundamental to many physics-related concepts because its laws hold true on any level, from the planetary to the atomic level. The potential energy of an object is measurable.

Answer:

well heat travels by conduction, convection, and radiation but I think it's 2.

Explanation:

heat travels to colder things trying to make a balanced temperature for both of the objects.

the ph is gonna be your value and the 4 is gonna be your main subject

so as the ph is your value u gonna ad your ph and 7 and 4 toghter then multiple your answer 2 times  because ph represent multiple and your value  

Answer:

9moles of hydrogen gas

Explanation:

To solve this problem, we write the reaction expression first;

                       2H₂   +   O₂    →     2H₂O

We have been given the number of moles of oxygen gas to be:

 Number of moles of oxygen gas  = 4.5moles

From the balanced reaction expression:

      1 mole of oxygen gas reacts with 2 moles of hydrogen gas

  4.5moles of oxygen gas will react with 4.5 x 2  = 9moles of hydrogen gas

Answer:

Q= Magnesium R= Chlorine

Explanation:

The element Q should be magnesium and R is chlorine.

An ionic compound is a compound that is formed by the combination of a metal and non-metal. Such bonds forms when there is a transfer of electrons from the metals to the non-metals. This leaves a net positive charge on the metal and a negative charge on the non-metal.

The electrostatic attraction leads to the formation of the bond.

 To solve this problem, the hypothetical compound is QR₂

       Mg                        Cl

     2 8 2                    2 8 7

So, Mg transfers 2 electrons to two atoms of chlorine.

 This leads to the formation of the compound MgCl₂

Answer: Photosynthesizing organisms use carbon dioxide and water to produce glucose.

Explanation:

Photosynthesis is a phenomenon in which green plants containing chlorophyll use sunlight as a source of energy to convert carbon dioxide and water to form glucose and oxygen.

Photosynthesis is the process used by plants, algae and certain bacteria to convert energy from sunlight and turn it into chemical energy in the form of glucose which is used a s a source of energy by many organisms.

[tex]6CO_2+6H_2O\overset{sunlight}\rightarrow C_6H_{12}O_6+6O_2[/tex]

Answer:

1.2 cm

Explanation:

The reason how I got my answer is by dividing 150 by 125 and that gave me 1.2 cm.

Answer:

a) the increase in internal energy is 3211.78 J

b) dU = 3854.14 J

c) dU[tex]_{T}[/tex] = 1927.06 J

Explanation:

Given the data in question;

Foe a diatomic gas, the degree of freedom are as follow;

lets consider the positional degree of freedom

transitional df = 3

rotational df = 2

vibrational ff = 1

now, the internal energy given by;

U = Nf × 1/2NKT = Nf×1/2×nRT

where Nf is the number of degree of freedom

N is Number of atoms or molecules

n = number of molecules

L is Boltzmann constant

R is universal gas constant

so change in internal energy , change in T is given by

dU =  Nf × 1/2 × nT dT

n = 2.37 moles

dT = 65.2 K

R = 8.314 J/mol.J

a)

Find the increase in internal energy if only translational and rotational motions are possible

since rotational and transitional motion are involved ;

Nf = 3(trasitional) + 2(rotational) = 5

so,

dU = 5 × 1/2  × nRdT

we substitute

dU = 5 × 0.5  × 2.37 × 8.314 × 65.2

dU = 3211.78 J

Therefore, the increase in internal energy is 3211.78 J

b)

Find the increase in internal energy if translational, rotational, and vibrational motions are possible.

Nf = 3 + 2 + 1 = 6

dU = 6 × 1/2  × nRdT

dU = 6 × 0.5  × 2.37 × 8.314× 65.2

dU = 3854.14 J

c)  

How much of the energy calculated in (a) and (b) is translational kinetic energy?

dU[tex]_{T}[/tex] = 3 × 0.5  × 2.37 × 8.314 × 65.2

dU[tex]_{T}[/tex] = 1927.06 J

Answer:

[tex]\%N=26.2\%\\\\\%H=7.5\%\\\\\%Cl=66.3\%[/tex]

Explanation:

Hello!

In this case, since the calculation of the percent composition of an element in a chemical compound is computing considering its atomic mass, subscript in the formula and molecular mass of the compound it is; for nitrogen, hydrogen and chlorine we have that ammonium chloride has a molar mass of 53.49 g/mol so the percent compositions are:

[tex]\%N=\frac{14.01*1}{53.49}*100\% =26.2\%\\\\\%H=\frac{1.01*4}{53.49}*100\% =7.5\%\\\\\%Cl=\frac{35.45*1}{53.49}*100\% =66.3\%[/tex]

Best regards!

The lethal dose and how ounces of soda in a can of soda is not given, however, the standard lethal dose and volume of soda are given as below:

Lethal dose: 10 gm of caffeine

The volume of soda per can =  12oz/can

Answer:

The correct answer is - 324.254 cans or round up to 325 cans. Ans.

Explanation:

Given:

2.57 mg caffeine / 1oz

12oz / 1can

Lethal dose: 10.0g or 10,000mg of caffeine

Solution:

Caffeine per soda can = (2.57 mg caffeine / 1oz) * (12oz / 1can) = 30.84 mg caffeine / 1can.

lethal dose would be in =

(10,000mg caffeine) * (1can / 30.84 mg caffeine) = 324.254 cans or round up to 325 cans. Ans.

Answer:

25 mM Tris HCl and 0.1% w/v SDS

Explanation:

A 10X solution is ten times more concentrated than a 1X solution. The stock solution is generally more concentrated (10X) and for its use, a dilution is required. Thus, to prepare a buffer 1X from a 10X buffer, you have to perform a dilution in a factor of 10 (1 volume of 10X solution is taken and mixed with 9 volumes of water). In consequence, all the concentrations of the components are diluted 10 times. To calculate the final concentration of each component in the 1X solution, we simply divide the concentration into 10:

(250 mM Tris HCl)/10 = 25 mM Tris HCl

(1.92 M glycine)/10 = 0.192 M glycine

(1% w/v SDS)/10 = 0.1% w/v SDS

Therefore the final concentrations of Tris and SDS are 25 mM and 0.1% w/v, respectively.

Answer:

I believe the correct answer is cold surfaces.

Explanation:

Answer:

C

Explanation:

Answer:

movement of charged particles through the wire .

Explanation:

When electricity is passed through the wire of electromagnet , moving electrons of the wire produces magnetic field . This magnetic field in increased due to high permeability of soft iron of the electromagnet . It is this magnetic field which creates magnetic force .

Answer: inside

Explanation:

Answer:

direct and indirect contact

Explanation:

if you touch a doorknob right after an infected person than you make be exposed to the disease.